In the forthcoming grant period we propose: (1) To continue our studies of the development of the avian visual system, taking advantage of the manipulability of certain parts of this system in chick embryos to determine such developmental features as the control of cell proliferation and the establishment of axial polarity in the optic tectum, the capacity of the system for regeneration and plasticity. (2) To extend the capabilities of the computer-system developed in our laboratory, and the quantitative analysis of neuroanatomical data. And (3) to maintain, and to continue to make available, this system to others in the visual sciences community who wish to use it, or to adapt the programs we have developed for their own purposes. The work is to be carried out at the Salk Institute for Biological Studies in La Jolla, California, where a new laboratory is being constructed for the Principal Investigator, which will contain all the necessary facilities for the effective prosecution of the research.